The Compass Lectures

Name: Henry Liu

Position: PhD Candidate in Physics

Title: Backlighting the Universe

Talk Description: The oldest light in the universe, the Cosmic Microwave Background, was released only 380,000 years after the Big Bang. Today, the CMB still fills the sky, passing through everything that formed afterwards. In this talk, I’ll show how astronomers and cosmologists can use the Universe’s “baby picture” as a giant backlight, and how this backlight allows us to study parts of the cosmos that are otherwise invisible, revealing the structure of the Universe on the largest scales.

Date: Friday, September 18, 2026

Time: 3:10 pm – 4:00 pm (talk and questions) 

Location: 230D Stephens Hall

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Name: Mark Zhu

Position: Graduate Student in Physics

Title: Adaptive Binning of Polarimetric Data: Tracing Low-Surface Brightness Extragalactic Magnetic Fields

Talk Description: Polarimetry — the study of measuring the rotation of polarized light as it passes through certain substances — can be used to infer the magnetic fields of galaxies and other astronomical events. These magnetic fields are crucial to the formation and large-scale structure of galaxies, and are thus important to map out with great accuracy. Developing these maps can be difficult and expensive due to the low amount of polarized light that normally reaches our detectors, so computational methods can be used to boost the signal of our data.”Binning” is a common technique used, where several pixels with low signal-to-noise ratios are combined to create a “superpixel” with a higher collective ratio. Here, I’ll present an adaptive binning technique specifically designed for astrophysical polarimetry I developed during my undergraduate years with Professor Susan Clark at Stanford University and Professor Enrique Lopez-Rodriguez at the University of South Carolina. We show that our binning algorithm is able to recover galactic magnetic fields with great accuracy and yield by testing it on simulated spiral galaxies. We also used the algorithm on real galaxies to recover their turbulent magnetic fields, which are too weak to see otherwise.

Date: Friday, September 25, 2026

Time: 3:10 pm – 4:00 pm (talk and questions) 

Location: 230D Stephens Hall

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Name: Alain Fauquex

Position: Graduate Student in Physics

Title: Where is All the Missing Mass? Using Quantum Sensors to Search for Dark Matter

Talk Description: Ordinary, “visible” matter makes up only about 15% of the matter in the universe; the remaining 85% remains unseen, and physicists still do not know what it is. One possible explanation is a hypothetical particle called the axion, which would pass through ordinary matter with almost no interaction, making it extremely difficult to detect. In my research, I build highly sensitive quantum devices similar to the superconducting qubits used in quantum computers to search for these particles. As part of the BREAD experiment, we try to convert axions into photons and then detect those photons using our sensors. Although axions have never been observed, detecting them would help explain one of the biggest mysteries in modern physics. In parallel, the same technology could be used for practical applications such as monitoring nuclear reactors, surveying nuclear accident sites, or detecting smuggled nuclear materials.

Date: Friday, October 2, 2026

Time: 3:10 pm – 4:00 pm (talk and questions) 

Location: 230D Stephens Hall

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Name: Natalie LeBaron

Position: PhD Candidate in Astronomy

Title: The (Life and) Death of Stars: Where the Elements Around Us Form

Talk Description: From the oxygen we breathe to the gold in our jewelry and the calcium in our bones, the majority of periodic table elements that make up our world are forged by stars. This talk explores how the universe transforms simple hydrogen into the rich diversity of atoms that build planets, life, and everything we see around us. Beginning their lives in vast clouds of gas and ending in massive explosions, we will discover how each star in the night sky creates and scatters ingredients for new worlds throughout their evolution.

Date: Friday, October 9, 2026

Time: 3:10 pm – 4:00 pm (talk and questions) 

Location: 230D Stephens Hall

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Name: Matthew Tao

Position: PhD Candidate in Physics

Title: Probing gravity with minute-scale atomic spatial superpositions

Talk Description: General relativity and quantum mechanics are two of the most successful theories in modern physics, yet attempts to unify them have been unsuccessful. Atom interferometers offer a way to directly probe the connection of quantum mechanics to gravity. They are usually operated in free fall, which limits their interrogation time and measurement schemes. Our group has shown that holding atoms in spatial superposition in an optical lattice is a powerful alternative to free-fall interferometers and are trying to improve its sensitivity. In this talk, I will explain how we build this trapped atom interferometer, maintain coherence for up to one minute, and use it to measure the gravity of Earth and of nearby masses.

Date: Friday, October 16, 2026

Time: 3:10 pm – 4:00 pm (talk and questions) 

Location: 230D Stephens Hall

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Name: Bashi Mandava

Position: PhD Candidate in Physics

Title: On the role of randomness in evolution

Talk Description: Our world is highly complex, and evolutionary models have shown time and again the importance of a stochastic interpretation to build a complete picture of the world, from microbial bacteria to airport hubs. In this talk, I’ll lay out the groundwork starting from the earliest experiments that revealed the role of randomness in evolving populations: Buri’s classic experiment tracking genetic drift in fruit fly populations, and the Luria-Delbrück experiment, which showed that bacterial mutations can occur randomly in absence of environmental pressure or selection. Both experiments established chance events in small populations can leave a lasting, measurable fingerprint. I’ll then build up the theoretical models that formalize this randomness, starting with genetic drift and the Wright-Fisher and Moran models and building up to the more detailed Fisher-KPP equations. Along the way, we’ll meet gene surfing, where the same randomness from small populations reappears at the leading edge of an expanding wave, letting a single lucky mutant ride the front to high frequency. Finally, I’ll explain how different regimes of dispersal, from short local hops to rare long-distance jumps, can lead to dramatically different dynamics, including populations that spread far faster than classical theory predicts.

Date: Friday, October 23, 2026

Time: 3:10 pm – 4:00 pm (talk and questions) 

Location: 230D Stephens Hall

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Name: Botho Paschen

Position: Project Scientist in LBL Physics Division

Title: Particle tracking detectors at high energy colliders

Talk Description: At high energy colliders, particles like protons or electrons interact, convert part of their energy into mass, and produce a plethora of new particles which fly away in all directions. These processes allow us to study the fundamental forces governing all known matter. To understand what exactly happens at the collisions the properties like charge, mass, and energy of all produced particles need to be measured as accurately as possible. Additionally, these experiments have to be repeated billions of times hunting for rare quantum processes. Advanced tracking detectors can track the paths of charged particles produced in intervals of mere nanoseconds using silicon chips similar to those of digital cameras and computer processors.

Date: Friday, October 30, 2026

Time: 3:10 pm – 4:00 pm (talk and questions) 

Location: 230D Stephens Hall

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Name: Jason Huskey

Position: Undergraduate Student in Physics and Mathemattics

Title: Laser Spectroscopy for Atomic & Nuclear Structure of Heavy Elements

Talk Description: Heavy elements are radioactive and often short-lived, so relatively little is known about their chemical and nuclear properties. In recent decades, advanced techniques in ion trapping and laser spectroscopy have enabled precise measurements of their masses, electron affinities, and nuclear shapes and sizes. These observables have important consequences for chemical bonding, nuclear medicine, and new physics beyond the Standard Model. This lecture will discuss certain goals, methods, progress, and future plans of the nuclear science programs at MIT and Berkeley Lab. Additionally, information on getting involved in experimental research in and beyond Berkeley will be provided.

Date: Friday, November 6, 2026

Time: 3:10 pm – 4:00 pm (talk and questions) 

Location: 230D Stephens Hall

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Name: Zhiquan Sun

Position: Postdoctoral Research in Physics

Title: Looking inside of the proton

Talk Description: I will start with how our understanding of “elementary particles” have changed over time, and introduce our current best description of the proton. I will then highlight what we do not understand about the proton, and what efforts particle physicists are making to “look inside the proton” to uncover its structure. This will include a brief introduction to quantum chromodynamics, the theory that describes the strong interactions between quarks and gluons, the fundamental particles that we believe make up the proton. I will also introduce the concept of effective field theory, which is the concept of using a controlled parameter expansion to improve theoretical precisions. The lecture will hopefully give the students a taste of what the current state of theoretical particle physics is.

Date: Friday, November 13, 2026

Time: 3:10 pm – 4:00 pm (talk and questions) 

Location: 230D Stephens Hall

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Name: Tamojeet Roychowdhury

Position: Graduate Student in Astronomy

Title: Where did Planets like Earth get their Water? Let’s Track Ices in the Nurseries of Stars and Planets

Talk Description: Cold, dense clumps of gas and dust in the interstellar medium eventually collapse to form stars and protoplanetary disks, from which planets like in our own Solar system arise. Elements in these cold cores can combine to form ices on the surface of dust grains, the dominant among which is water ice. These ices eventually settle on the planets forming around the star, making it important to study their formation and processing in the dense clumps. But spatially resolving the ice distribution often requires expensive spectroscopy making it hard to do for many regions. Fortunately, NASA’s new space telescope, SPHEREx, has been doing an all-sky low resolution spectroscopic survey, enabling creation of large-area ice maps for the first time. In this lecture I will talk about some first results of ice evolution in these dense clumps, and how both a larger observational sample and stronger numerical modelling will help further our understanding of how these ices grow or get destroyed during star and planet formation.

Date: Friday, November 20, 2026

Time: 3:10 pm – 4:00 pm (talk and questions) 

Location: 230D Stephens Hall

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Name: Ethan Levin

Position: Graduate Student in Mechanical Engineering

Title: The Physics of Wildfires

Talk Description: Every California resident knows the ubiquity and destructive power of wildfires. Whether it be through images of massive flames licking out of remote forests, or the smoke that follows, it’s hard to avoid these conflagrations in the latter half of the year. But what is our understanding of the physical mechanisms that make them what they are? In this talk, we will start from the basics and history of mass fires, and end with how recent discoveries have changed the way in which we model and study them.

Date: Friday, December 4, 2026

Time: 3:10 pm – 4:00 pm (talk and questions) 

Location: 230D Stephens Hall

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